We're In For A Dust-up

After All The Wet, Tropical Activity In The Caribbean And Gulf Of Mexico This Month, South Florida Is About To Be Hit By A Huge Cloud Of Sand From The Sahara. The Sandstorm Is Expected To Hover Over Us Early Next Week.

July 22, 2005|By Ken Kaye Staff Writer

As if this hurricane season wasn't tumultuous enough, South Florida is about to get hit by a sandstorm.

By Monday or Tuesday, a Sahara dust outbreak, or a cloud of what originally was African sand carried across the Atlantic on the back of a tropical wave, is expected to settle over the region for about 12 hours, forecasters said.

It might turn the skies milkier and leave a light coating of reddish-brown dust on your car, the result of a small amount of iron content. It also could make the sunrise and sunset spectacular, said Jim Lushine of the National Weather Service in Miami.

"It's just kind of an interesting phenomenon," he said. "You might see it better in the morning, when the angle of the sun is low."

On the other hand, if concentrated enough, the outbreak could raise the air quality index into the unhealthy range for people with respiratory problems, said Ken Larson, a natural resource specialist with the Broward County Environmental Protection Department.

"If there are adverse concentrations, we would put out a health advisory," he said. "If somebody is subject to a respiratory condition, if they see hazy skies, they might want to take a little more precaution, not participate in strenuous activity and stay indoors."

Dust outbreaks, which are most common in early July, start when tropical waves lift sand from the Sahara to about 10,000 feet, where it is reduced to even smaller particles. The dust then drifts west on a dry tropical wave, as opposed to a moist tropical wave, which can spin into a hurricane.

The dust cloud aiming this way is huge, about 2,500 miles from west to east and 1,500 miles from north to south, or almost as big as the United States, Lushine said.

FOR THE RECORD - CORRECTION PUBLISHED SATURDAY, JULY 23, 2005.A graphic on Page 1A of Friday's edition incorrectly described the size of a dust storm over the Atlantic Ocean. The storm stretches 1,500 miles from south to north and 2,500 miles from east to west.

South Florida should see its western edge, which is where the tropical wave is embedded, but "they'll notice it more in the Caribbean, like in San Juan," Lushine said.

By today, the outbreak should be about 1,400 miles east of Miami, moving west at 345 miles per day, about the same pace as a tropical system.

Because the Sahara dust carries some pathogens, it might cause harm to coral reefs, particularly in the Caribbean, said Bernhard Riegl, an associate professor at Nova Southeastern University's Oceanographic Center. Those pathogens, he said, include fungi, spores and bacteria, but the dust can haul even bigger objects. "Entire desert locusts, the insects, have made it across the Atlantic to the Windward Islands."

So far, there is no evidence the pathogens harm humans, although on the Caribbean island of Trinidad an abnormal number of infants have asthma problems, he said.

One good side effect: "It's difficult for tropical storm development to occur in these dust outbreaks," Lushine said.